Dump bodies of the integral type are well known. However, the known dump bodies are heavy due mainly to their own heavy substructure or to the additional subframe which is required on the vehicle to support them. Known dump bodies are also heavy because their floors are made of a steel plate of uniform thickness throughout and great enough to have sufficient rigidity and also to resist abrasion during loading and unloading. Furthermore, the known dump bodies are generally formed of sharp corners which retain gravel and dust and must be regularly clean, thus adding to the maintenance cost.